Gaseous discharge amplifier tube



Dec. 18,y 1934. G JOBST ET AL 1,984,877

GASEOUS DISCHARGE AMPLIFIER TUBE Filed NOV. 20, 1931 jm mL- Juk---5--1||+ INVENTORS GNTHER JOBST FPJTZ MICHELSSEN A RNEY BY Wig-@WSW Patented Dec. 18, 1934 UNITED vSTAT PATENT OFI-*ics GAsEoUs DISCHARGE AMPLIFIER TUBE Gnther Jobst, Fritz Michelssen, and Waldemar Wehnert, Berlin, Germany, assignors to Telefunken Gesellschaft fr IDrahtlose ,Telegraphie m. b. H., Berlin, Germany, a corporation of Germany I Application November 20,1931, seria1No.576,292

InGermany November Z1, 1930 7 claims.

Itis known that if the electrodes are mounted 4in .a suitable manner considerable gains are obtainable with the gaseous discharge type of` amplifier tubes. One well known electrode arrangement in gaseous discharge amplifiers, forv instance, is based upon the principle of utilizing for the electron source a constant and quiet.

o'wingJto the amplier anode. However, one

disturbing effect inall of these schemes known in the prior art `is the productionV of `relatively strong grid currents'. rWhile in modern ampli-V er arta limitation of the grid currents to noty over l0-,6,milliamperes is imperative, glow dischargeY or gaseous .conduction ampliiieri'tubes,` of

the kindjus't referred to exhibit the presence of Y considerably larger grid currents;

Now, in order .to minimize these grid-currents it has previously beenv suggested to` so dispose the anode of the glow discharge gap that the amplierielectrodes, especially the grid, will be shielded thereby fromnffast. electrons.r Nevertheless, troublesome grid currents have been noted in "the arrangements disclosed in the earlier art, and these are ascribable to ionization of the gas caused by ionic impacts. Now, the present invention discloses ways and means to eliminate the troublesome eifect of these currents. According to this invention, the gaseous conduction amplier tube, contradistinct to what has been known before, is provided not with a single grid, but rather two or three grids mounted in the space between the amplifierr anode and the glow-discharge gap. By the judicious choice of the biasing potentials to be applied to the auxiliary or supplemental grid or grids it is possible topreclude disturbing charges or currents from the control grid proper.

- If the auxiliary or supplementary grid, as will be noted, is given a biasing potential which is negative relative to the control gridthis auxil-r iary grid acts as a means whereby the ions caused by impact ionization of the disturbing gas admixtures are extracted or absorbed, and the result is that the alternating potentials applied to the control grid and to be amplified will no longer be influenced by this grid curin the form of a dark or.

(Cl. 179-171) i rent, Suchk ion absorbing action ,of the auxilgy iary grid vwill be particularly favorable when the inte1-el ectrode distances and the gas pressure are so chosen that only a few mean free paths of the electrons are feasible s o that practically noA impact ionization will `occur vin Ithe vamplifier space. In this yarrangement the yeffect of the, ion-collecting .grid would `be coniinedto lthe ,ab-l

sorption of ions which are produced byffthv action of electrons in the ypath between the glow discharge gap andthe amplifier electrodes, l

However, whenever the gas filling of such `a, glow discharge amplifierl tube is extremely pure, the disturbance residing in ionic currents tothev lgrid as above described will no longer arise,

though, on the other hand it becomesrnoticef able that the slope of ther characteristic of `such an amplier is greatly impaired compared withy what itv is in .the presence of slightadmixturesofextraneous gases. Also where extremelypure gases areconcerned, the provision ofwa gridoifers substantial advantages. ,yf choosin'ga suitable potential preferably slightly.posi!l tive for the second grid itis possible by Villille of its presenceto avoid thespace-chargedue -to the` electrons, in other'I words, to strictly define the'. distance between cathode and anode'.`. ln' thisway `conditionsare made so thateven gas;

eous 4` condi1ction amplifiers containing pure i gases having characteristics with slopes ',of'.,a, useful order'loflmagnitude.are obtainable;4 'j

For purposes'of illustration the faccmparying drawing shows diagrammatically one embodiment of the invention. The tube shown in the drawing comprises a sealed envelope 1 con-'- taining ygas at the proper pressure and having an anode 2 and a glow discharge gap with two electrodes 3 so spaced that a glow discharge can be maintained between them by a suitable source of current, such as a battery 4. The anode is maintained at the proper positive potential relative to the electrodes of the glow discharge gap by abattery 5 with its negative pole connected to one of the glow discharge gap electrodes 3 and its positive pole connected through a load, such as the transformer 6, to the anode 2.

The alternating voltages from any suitable source may beimpressed thru a transformer 7 on a control grid 8 adjacent the anode, and an auxiliary grid 9 is mounted between the control grid and the glow discharge gap. The potential of the auxiliary grid is maintained constantv by suitable means, such as a biasing battery 10 connected to the auxiliary grid y9 and preferablyto an electrode of the glow discharge gap. In the drawing the auxiliary grid 9 is shown connected to the negative pole of the biasing battery, so that the grid is negative with respect to the glow discharge gap electrodes and also to the control grid 8 connected to one of these electrodes, but the connection may be reversed when it is desired to make the auxiliary grid a space charge grid and maintain it positive as may be desirable in some cases, for example, where the gas in the envelope 1 is very pure.

I claim:

1. A gaseous conduction amplifier comprising a sealed envelope containing a gaseous atmosphere and enclosing an electron source comprising a pair of gaseous discharge electrons spaced to form a gap in which a discharge may be maintained, a plate electrode, a control grid, and an auxiliary grid between said control grid and said electron source positively biased with respect to both of said discharge electrodes.

2. A gaseous conduction ampliiier comprising a sealed envelope containing a gaseous atmosphere, a pair of electrodes mounted in said envelope to form a glow discharge gap, a plate, a control grid, an auxiliary grid between said discharge gap and said control grid and biased to enable said auxiliary grid to trap ions appearing in said envelope, the interelectrode distances and the gas pressure being so related that impact ionization in the space between said grids and said plate is substantially absent.

' 3. A gaseous conduction amplier comprising a sealed envelope containing a gaseous atmosphere and enclosing an electron source comprising a pair o f electrodes spaced to form a gap in which a discharge may be maintained, a plate electrode, a control grid, and a space charge grid between said` control grid and said electron source, the spacing between said anode and said control grid and the pressure of said atmosphere being .so related that impact ionization in the space between them is substantially absent. v

4. A gaseous conduction amplier comprising a sealed envelope containing a gaseous atmosphere and enclosing an electron source comprising `a pair of gaseous discharge electrodes spaced to forma gap in which a discharge may be maintained, 'a plate electrode, a control grid adjacentpsaid anode, and a space charge grid adjacent said electron source and positively biased with reference to both of said discharge electrodes, and means for supplying a constant positive potential to said space charge grid.

5. A gaseous conduction ampliercomprising a sealed envelope containing a gaseous atmosphere and enclosing an electron sourcecompris- .ing a pair of electrodes mounted in said envelope to form a discharge gap, a plate, a pair of grids between said discharge gap and said plate, the grid adjacent the anode being directly connected through an impedance to one of the discharge electrodes, and the grid adjacent the discharge gap being directly connected through a source of biasing potential to the other discharge electrode.

6. A gaseous conduction discharge device comprising a sealed envelope containing a gas at low pressure and enclosing a pair of electrodes spaced to form a gap in which a gaseous conduction discharge may be maintained, a plate, a control grid adjacent said plate, a transformer secondary connected to one of said electrodes and to said control grid, an auxiliary grid between said electrodes and said control grid, a source of constant potential connected to the other of said electrodes and to said auxiliary grid, a source of higher potential connected to said other electrode and to said plate, a source of potential connected to `both said electrodes to maintain a discharge between them, andA means for impressing a variable potential on said transformer secondary.

7. A gaseous conduction discharge device comprising a sealed envelope containing a gaseous atmosphere, a pair of electrodes disposed in spaced parallel relation mounted Within said envelope and forming a glow discharge gap, a source of potential connected between said discharge gap electrodes, a plate, a source of potential connected between the first mentioned source and the plate, a plurality of grids extending in planes at right angles to the discharge electrodes and interposed between said discharge gap and said plate, and means for impressing a variable potential on one of said grids, and means for impressing a constant potential on the other of said grids.

FRITZ MICHELSSEN. GNTHER JoBsT. WALDEMAR WEHNERT. 

